Methods and Apparatus for Predicting and Confirming Drug-Induced Thrombocytopenia Through Particle Detection with Dynamic Light Scattering

Abstract

Dynamic light scattering (DLS)-based particle testing is used for screening to predict drug-induced complications with heparin and other compounds known to lead to thrombocytopenia in many patients. The measurement of particle content is used to both predict as well as confirm drug-induced thrombocytopenia (“DIT”).

1 . A method of predicting the risk of drug-induced thrombocytopenia (DIT) comprising the steps of:
 a. obtaining a first patient sample from a patient, the patient sample comprising platelets;   b. adding to the first patient sample a compound that is suspected to cause a reaction with platelets in the sample;   c. analyzing the patient sample to determine particle content;   d. based on the determined particle content, determining platelet activation in the sample as a measure of the risk of DIT.   
     
     
         2 . The method according to  claim 1  in which analysis of the sample to determine particle content is done with dynamic light scattering (DLS) and wherein the DLS analysis measures particle content in the sample for all particles contained therein. 
     
     
         3 . The method according to  claim 2  in which the particle content in the patient sample comprises platelets, microparticles and aggregates. 
     
     
         4 . The method according to  claim 2  including the step of comparing the determined platelet activation to predetermined thresholds. 
     
     
         5 . The method according to  claim 4  further comprising detecting a change in size distribution of particles in the sample. 
     
     
         6 . The method according to  claim 5  including detecting a change of relative content of particles smaller than 550 nm and a change in relative content of particles larger than 500 nm. 
     
     
         7 . The method according to  claim 2  in which platelet activation in the sample is determined by DLS determination of the mean particle radius. 
     
     
         8 . The method according to  claim 2  including using DLS to monitor changes in platelet activation over time. 
     
     
         9 . The method according to  claim 2  further confirming DIT according to the steps comprising:
 a. obtaining a second patient sample from the patient; 
 b. obtaining a first sample of platelet rich plasma (PRP) from a pedigree donor; 
 c. adding to the first sample of PRP from the pedigree donor a compound that is suspected to cause a reaction with platelets in the PRP; 
 d. combining the second patient sample with the first sample of PRP from the pedigree donor; 
 e. analyzing the combination formed in step d. with DLS to determine platelet activation. 
 
     
     
         10 . The method according to  claim 9  in which the analysis in step e. is compared to a calculated DLS result combining the relative contributions of the first sample of PRP from the pedigree donor and the second patient sample from the patient. 
     
     
         11 . The method according to  claim 9  including the step of comparing the determined platelet activation to predetermined thresholds. 
     
     
         12 . The method according to  claim 9  in which the compound that is suspected to cause a reaction with platelets is heparin. 
     
     
         13 . A method of detecting the assaying particles in a patient sample containing platelets in order to confirm drug-induced thrombocytopenia (DIT), the method comprising the steps of:
 a. obtaining a first patient sample from a patient;   b. obtaining a second sample from a pedigree donor, the second sample comprising platelet rich plasma (PRP);   c. adding to the first patient sample a compound that is suspected to cause a reaction with the platelets;   d. combining the second sample with the first sample;   e. analyzing the combination formed in step d using dynamic light scattering (DLS) to determine platelet activation;   f. comparing the determined platelet activation to predetermined thresholds to determine DIT.   
     
     
         14 . The method according to  claim 13  wherein the DLS analysis comprises analysis of all particles in the combination. 
     
     
         15 . The method according to  claim 14  in which the combination comprises platelets, microparticles and aggregates. 
     
     
         16 . The method according to  claim 14  in which step e. further comprises detecting a change in size distribution of particles. 
     
     
         17 . The method according to  claim 16  including detecting a change of relative content of particles smaller than 550 nm and a change in relative content of particles larger than 500 nm. 
     
     
         18 . A method of assessing drug-induced thrombocytopenia (DIT) in a patient sample containing platelets, the method comprising the steps of:
 a. obtaining a first patient sample;   b. adding to the first patient sample a compound that is suspected to cause a reaction with platelets in the sample;   c. analyzing the first patient sample using dynamic light scattering (DLS) to determine particle content;   d. based on the determined particle content, determining platelet activation in the first patient sample and comparing the platelet activation to a predetermined threshold to thereby determine if DIT is an indicated risk;   e. if DIT is an indicated risk in step d.:
 i. obtaining a second patient sample; 
 ii obtaining a first sample of platelet rich plasma (PRP) from a pedigree donor; 
 iii. adding to the first sample of PRP from the pedigree donor a compound that is suspected to cause a reaction with platelets in the PRP; 
 iv. combining the second patient sample with the first sample of PRP from the pedigree donor; 
 v. analyzing the combination formed in step e.iv. with DLS to determine platelet activation to thereby confirm that the compound that is suspected to cause a reaction with platelets in the sample may cause DIT in the patient. 
   
     
     
         19 . The method according to  claim 18  in which the DLS analysis in steps c. and e.v. comprises detecting a change in size distribution of all particles in the sample. 
     
     
         20 . The method according to  claim 19  including detecting a change of relative content of particles smaller than 550 nm and a change in relative content of particles larger than 500 nm.